Control of Pythium spp. and Pythium Blight of Turfgrass with Fosetyl Aluminum. P. L. Sanders, Senior Research Associate, Department of Plant Pathology, Pennsylvania State University, University Park 16802. W. J. Houser, Research Technologist, and H. Cole, JR., Professor, Department of Plant Pathology, Pennsylvania State University, University Park 16802. Plant Dis. 67:1382-1383. Accepted for publication 6 July 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1382.

Fosetyl aluminum showed no toxicity to 25 isolates of Pythium, representing eight species, on potato-dextrose agar amended with 1, 10, and 100 μg a.i./ml agar. Field control of Pythium blight with fosetyl aluminum was evaluated on Pennfine perennial ryegrass (Lolium perenne L.). At 1 wk postspray, 114 and 228 g/93 m² provided 87 and 100% symptom suppression, respectively. Residual efficacy diminished gradually, and at 4 wk posttreatment, the 228-g rate provided 43% control. In the absence of direct fungitoxicity to species of Pythium, field control of Pythium blight on ryegrass may result from elicitation of antifungal responses in the host.